Reflective Thin-Film Transistor Gate for LCD Light Transmittance
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Solution Overview
Problem
In side-light emitting liquid crystal displays, the low reflectivity of the gate metal layer in thin film transistors reduces light transmittance, as most light is either absorbed or reflected back, leading to a transmittance rate less than 20%, which affects the display quality.
Innovation Solution
A thin film transistor with a reflective coating having a reflectivity of at least 80% is integrated, where the coating is a metal with a mirror surface structure, typically silver or aluminum, applied using electroplating, to enhance light reflection and reduce absorption by the opaque gate metal region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate metal layer made of aluminum or molybdenum is used, then the transistor functionality is achieved, but the light transmittance is reduced because the metal layer is opaque and reflects less than 20% of light
Solution Approach 1:
The gate structure is segmented into three distinct layers: a lower gate electrode (aluminum or molybdenum), a reflective coating layer (silver or aluminum with mirror surface), and an upper gate electrode. This segmentation allows each layer to perform its specific function - the lower electrode provides transistor functionality, the reflective coating maximizes light reflection, and the upper electrode completes the gate structure.
Solution Approach 2:
The gate structure uses composite materials combining different metal properties. The reflective coating layer uses silver or aluminum with a mirror surface structure to achieve high reflectivity (greater than 20%), while the gate electrodes use aluminum or molybdenum for electrical functionality. This composite approach optimizes both electrical performance and optical properties.
2Loss of energy
If the gate metal layer reflects light back to the backlight reflection plate, then some light is recovered, but the overall light transmittance remains low because most light is still shielded by the opaque metal layer
Solution Approach 1:
The invention converts the harmful effect of the opaque gate metal layer blocking light into a beneficial effect by adding a reflective coating. Instead of light being absorbed or scattered by the metal layer, the mirror surface structure reflects light back through the liquid crystal layer, transforming the blocking effect into a light-recycling mechanism that improves overall transmittance.
Solution Approach 2:
The reflective coating layer acts as an intermediary between the opaque gate metal layer and the light. It mediates the interaction by reflecting light that would otherwise be blocked, enabling light to interact with the liquid crystal layer even when the gate is in the off state, thereby improving light utilization efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The high reflectivity coating ensures that most light is reflected back to the backlight, increasing the transmittance rate and improving the overall performance of the liquid crystal display by minimizing light loss.
Implementation Method 1
a reflective coating arranged above the gate dielectric layer... a reflectivity of the reflective coating to visible light is greater than or equal to 80%... the light emitted to the gate metal layer may be shielded by the metal layer... the metal layer is able to reflect the light back to the backlight reflection plate
Implementation Method 2
the reflective coating is a metal with a mirror surface structure... applied using electroplating
Data Source
AI summary
The present disclosure provides a thin film transistor, a manufacturing method of the thin film transistor, and a liquid crystal display. The thin film transistor includes a substrate; an active region arranged above the substrate; a channel region arranged in a center of the active region; source and drain regions arranged on two sides of the channel region; a gate dielectric layer arranged above the channel region; a reflective coating arranged above the gate dielectric layer; a gate metal arranged above the reflective coating; an interlayer dielectric layer covering the gate metal, the active region, and the substrate; and a source/drain metal layer passing through the interlayer dielectric layer and electrically connecting with a surface of the source and drain regions.